1. Field of the Invention
The present invention relates to a write control circuit, and more particularly to a write control circuit for performing laser diode control with optimized functional distribution.
2. Description of the Related Art
A background color image forming apparatus generally forms a color image by superimposing a plurality of color images.
FIG. 1 is a block diagram illustrating a configuration of a control circuit of a background color image forming apparatus 100. As shown in FIG. 1, the background color image forming apparatus 100 includes a control system having an engine control unit 132 such as a CPU, an image processing circuit 23, write control circuits 140K, 140C, 140Y, and 140M for four colors, namely black, cyan, yellow, and magenta (hereinafter, referred to as K, C, Y, and M, respectively, as necessary), and laser diode (hereinafter, referred to as LD as necessary) driver circuits 128 for K, C, Y, and M controlled by the write control circuits 140K, 140C, 140Y, and 140M, respectively. The background color image forming apparatus 100 further includes an optical writing unit 1, a scanner 21 and a printer driver 22.
The image processing circuit 23 performs an image processing operation on image information supplied by the scanner 21 or an image data signal supplied by the printer driver 22 to prepare image data for the four colors, and supplies the respective write control circuits 140K, 140C, 140Y, and 140M with the image data for the respective colors. The image processing operation of the image processing circuit 23 includes color data conversion from RGB to CMYK, rotation, editing, and so forth.
The respective write control circuits 140K, 140C, 140Y, and 140M are supplied with control information from the engine control unit 132.
The background image forming apparatus 100 has a general configuration such that although the four write control circuits 140K, 140C, 140Y, and 140M have the same configurations, the four write control circuits 140K, 140C, 140Y, and 140M are separately provided for the respective colors.
Generally, in recent years, a write control circuit has been configured as an integrated circuit (hereinafter, referred to as IC). Since development of an IC incurs a huge cost, it is not practical to provide an image forming apparatus with respective ICs for a plurality of similar functions.
Therefore, in general, a single write control IC that covers all functions needed for forming images in respective colors has been developed, and the write control IC is mounted to an image forming apparatus for each of the colors.
Another background image forming apparatus includes respective write control mechanisms for a plurality of image forming colors to control respective light sources. The respective write control mechanisms include a write image processing mechanism for processing image data for base colors, an LD control mechanism including an LD driver for controlling an LD being the light source, and a synchronization detection control mechanism for detecting a write start position in a main scanning direction. The respective write control mechanisms are configured as respective ICs.
However, the write control mechanisms may include a function that does not need to be included for each of the image forming colors. For example, a function for managing writing timing for all the image forming colors does not need to be included in each of the write control mechanisms. Such a function could be satisfactorily included in one of the write control mechanisms.